Ensure that GADLite is destroyed.

The FooterActionsController asks for a new
GlobalActionsDialogLite each time it is attached, and then that
it properly destroyes the GADLite each time it is detached.

GADLite registers listeners each time it is constructed. Prior to this
change, GADLite was constructed with each FooterActionsController, but
never had its #destroy method called. For the sake of semantic
correctness, we never reuse the GAD and instead create new one when
it is needed.

Fixes: 219535221
Test: manual && atest SystemUITests

Change-Id: Iab9aeb294e5995944a7c619013adccb8b36a3df9